The internet and WWW-he terms World Wide Web (WWW) and the Internet

the World Wide Web is just one common area for information exchange, facilitated by global computer networks — or the Internet. You connect to this Internet to access the Web, but the Internet is just the connection between countless, separate servers, computers, and devices.

1. The Internet and WWW 1

2. 1.0 Introduction to internet The Internet or “Net” (network of networks) is the largest computer network in the world that connects billions of computer users. The word internet comes from combination between “ interconnection” and “Network ”. Network is a collection of computers and devices connected via communication channels and transmission media allow to share resources (hardware, software, data, information). Generally nobody own internet . 2

3. 1.0 Introduction to internet … The vast collection of computer networks which form and act as a single huge networks for transport of data and messages across distances which can be anywhere from the same office to anywhere in the world. The internet is the world’s largest WAN and is made up of various nodes that connects via communication media all over the world. This allows all nodes to connect and communicate with one another. It also allows for various services, such as the world wide web and email to be hosted over or work on the internet . 3

4. 1.0 Introduction to internet … Internet is defined as an Information super Highway, to access information over the web. However , It can be defined in many ways as follows: Internet is a world-wide global system of interconnected computer networks . Internet uses the standard Internet Protocol (TCP/IP ) . Every computer in internet is identified by a unique IP address . IP Address is a unique set of numbers (such as 110.22.33.114) which identifies a computer location. A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name . For example, a DNS server will resolve a name http:// www.marymathacollege.ac.in to a particular IP address to uniquely identify the computer on which this website is hosted. Internet is accessible to every user all over the world. 4

5. 1.0 Introduction to internet … 5

6. 1.0 Introduction to internet … The Internet, World Wide Web (WWW) and information super highway have penetrated into lives of millions of people all over the world. The Internet is a network made up of thousands of networks worldwide. Obviously , these networks are composed of computers and other intelligent and active devices. In fact, Internet is an example of self-regulating mechanism and there is no one in-charge of the Internet. There are organizations which are entrusted to develop technical aspects of this network, but no governing body is in control. Private companies own the Internet backbone, through which Internet traffic or data flows in the form of text, video, graphics, sound image etc. All computers on the Internet communicate with one another using the Transmission Control Protocol/Internet Protocol architecture, abbreviated to TCP/IP , based on client/server architecture . This means that the remote server machine provides files and services to the user ' local client machine. Software can be installed ort a client computer to take advantage of the latest access technology . 6

7. 1.0 Introduction to internet … A wide variety of services, namely, electronic mail, file transfer, vast information resources, interest group membership, interactive collaboration, multimedia displays, real-time broadcasting, shopping opportunities, and many more are available on the Internet. To provide all these services, the Internet consists primarily of a variety of access protocols. Many of these protocols feature programs that allow users to search for and retrieve material made available by the protocol. Transmission Control Protocol/Internet Protocol ( TCP/IP ) is the protocol suite developed for the Internet . 7

8. 1.1 internet : Evolution The concept of Internet was originated in 1969 and has undergone several technological & Infrastructural changes as discussed below: The origin of Internet devised from the concept of Advanced Research Project Agency Network (ARPANET) . ARPANET was developed by United States Department of Defense. Basic purpose of ARPANET was to provide communication among the various bodies of government. Initially , there were only four nodes , formally called Hosts. In 1972, the ARPANET spread over the globe with 23 nodes located at different countries and thus became known as Internet. By the time, with invention of new technologies such as TCP/IP protocols, DNS, WWW, browsers, scripting languages etc.,Internet provided a medium to publish and access information over the web. 8

9. 1.2 internet : Advantages … Internet covers almost every aspect of life, one can think of. Here , we will discuss some of the advantages of Internet : 9

10. 1.2 internet : Advantages … Internet allows us to communicate with the people sitting at remote locations. There are various apps available on the wed that uses Internet as a medium for communication. One can find various social networking sites such as : Facebook Twitter Yahoo Google + Flickr Orkut One can surf for any kind of information over the internet . Information regarding various topics such as Technology, Health & Science, Social Studies, Geographical Information, Information Technology, Products etc can be surfed with help of a search engine . 10

11. 1.2 internet : Advantages … Apart from communication and source of information, internet also serves a medium for entertainment. Following are the various modes for entertainment over internet . Online Television Online Games Songs Videos Social Networking Apps Internet allows us to use many services like : Internet Banking Matrimonial Services Online Shopping Online Ticket Booking Online Bill Payment Data Sharing E-mail Internet provides concept of electronic commerce, that allows the business deals to be conducted on electronic systems 11

12. 1.3 internet : disadvantages … However , Internet has proved to be a powerful source of information in almost every field, yet there exists many disadvantages discussed below: 12

13. 1.3 internet : disadvantages … There are always chances to loose personal information such as name, address, credit card number. Therefore , one should be very careful while sharing such information. One should use credit cards only through authenticated sites. Another disadvantage is the Spamming . Spamming corresponds to the unwanted e-mails in bulk. These e-mails serve no purpose and lead to obstruction of entire system. Virus can easily be spread to the computers connected to internet. Such virus attacks may cause your system to crash or your important data may get deleted. Also a biggest threat on internet is pornography . There are many pornographic sites that can be found, letting your children to use internet which indirectly affects the children healthy mental life. There are various websites that do not provide the authenticated information . This leads to misconception among many people. 13

14. 1.4 INTERNET ADDRESSES Each day there are over a billion emails and search requests sent over the internet . But how does the data know where to go? How do we make sure that the data goes to the intended receiver and the correct destination? Every computing device that is connected to the internet receives a unique address, much like your street address. This address is called, an internet protocol address or IP address . Whenever a message is sent over the network, it is sent to a device’s IP address . The most common type of IP address is known as an IPv4 (internet Protocol Version 4) in which each number can range between 0 and 255, and is be represented by 1 byte (or 8 bits) of information. The IP address is made up of four sets of these numbers, separated by dots . 14

15. 1.4 INTERNET ADDRESSES : An IP address graphic 15

16. 1.4 INTERNET ADDRESSES … IP addresses are difficult to remember. For example, an IP address for Facebook could be 185.60.219.35 , while an IP address for Google could be 216.58.223.3 . To make it easier to find a specific website or, websites make use of domains. A domain is a unique name that may be linked to an IP address . A domain name is the part of a network that identifies itself as belonging to a particular person or company, for example, the SABC, SARS, and so on. 16

17. 2.0 Intranet Intranet is defined as private network of computers within an organization with its own server and firewall. Moreover we can define Intranet as: Intranet is system in which multiple PCs are networked to be connected to each other. PCs in intranet are not available to the world outside of the intranet . Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intrane t. Every computer in internet is identified by a unique IP address. Each computer in Intranet is also identified by a IP Address, which is unique among the computers in that Intranet . 17

18. 2.0 Intranet … 18

19. 2.1 Intranet : Benefits Intranet is very efficient and reliable network system for any organization. It is beneficial in every aspect such as collaboration, cost-effectiveness, security, productivity and much more. 19

20. 2.1 Intranet : Benefits … Communication Intranet offers easy and cheap communication within an organization. Employees can communicate using chat, e-mail or blogs . Time Saving Information on Intranet is shared in real time. Collaboration Information is distributed among the employees as according to requirement and it can be accessed by the authorized users, resulting in enhanced teamwork . Platform Independency Intranet can connect computers and other devices with different architecture . Cost Effective Employees can see the data and other documents using browser rather than printing them and distributing duplicate copies among the employees, which certainly decreases the cost . 20

21. 2.1 Intranet : Benefits … Workforce Productivity Data is available at every time and can be accessed using company workstation. This helps the employees work faster . Business Management It is also possible to deploy applications that support business operations. Security Since information shared on intranet can only be accessed within an organization, therefore there is almost no chance of being theft . Specific Users Intranet targets only specific users within an organization therefore, once can exactly know whom he is interacting. Immediate Updates Any changes made to information are reflected immediately to all the users. 21

22. 2.2 Intranet : Issues Apart from several benefits of Intranet , there also exist some issues . These issues are shown in the following diagram: 22

23. 2.3 Intranet : Applications Intranet applications are same as that of Internet applications. Intranet applications are also accessed through a web browser. The only difference is that, Intranet applications reside on local server while Internet applications reside on remote server. Here , we've discussed some of these applications : 23

24. 2.3 Intranet : Applications … 24

25. 2.3 Intranet : Applications … Document publication applications Document publication applications allow publishing documents such as manuals, software guide, employee profits etc. without use of paper . Electronic resources applications It offers electronic resources such as software applications, templates and tools, to be shared across the network . Interactive Communication applications Like on internet, we have e-mail and chat like applications for Intranet, hence offering an interactive communication among employees . Support for Internet Applications Intranet offers an environment to deploy and test applications before placing them on Internet. 25

26. 2.4 Intranet : Internet vs. Intranet Apart from similarities there are some differences between the two. Following are the differences between Internet and Intranet : 26 Intranet Internet Localized Network. Worldwide Network Doesn't have access to Intranet Have access to Internet. More Expensive Less Expensive More Safe Less Safe More Reliability Less Reliability

27. 3.0 Extranet Extranet refers to network within an organization, using internet to connect to the outsiders in controlled manner. It helps to connect businesses with their customers and suppliers and therefore allows working in a collaborative manner. 27

28. 3.1 Extranet : Implementation Extranet is implemented as a Virtual Private Networks (VPN) because it uses internet to connect to corporate organization and there is always a threat to information security. VPN offers a secure network in public infrastructure ( Internet ). 28

29. 3.1 Extranet : Implementation … Key Points The packet is encapsulated at boundary of networks in IPSEC complaint routers . It uses an encryption key to encapsulate packets and IP addresses as well . The packet is decoded only by the IPSEC complaint routers or servers . The message is sent over VPN via VPN Tunnel and this process is known as tunneling . VPN uses Internet Protocol Security Architecture (IPSEC) Protocol to provide secure transactions by adding an additional security layer to TCP/IP protocol . 29

30. 3.1 Extranet : Implementation … This layer is created by encapsulating the IP packet to a new IP packet as shown in the following diagram 30

31. 3.2 Extranet : Benefits Extranet proves to be a successful model for all kind of businesses whether small or big. 31

32. 3.3 Extranet : Issues Apart for advantages there are also some issues associated with extranet. These issues are discussed below: Hosting Where the extranet pages will be held i.e. who will host the extranet pages. In this context there are two choices: Host it on your own server . Host it with an Internet Service Provider (ISP) in the same way as web pages. But hosting extranet pages on your own server requires high bandwidth internet connection which is very costly. Security Additional firewall security is required if you host extranet pages on your own server which result in a complex security mechanism and increase work load . Accessing Issues Information can not be accessed without internet connection. However , information can be accessed in Intranet without internet connection . Decreased Interaction It decreases the face to face interaction in the business which results in lack of communication among customers, business partners and suppliers. 32

33. 3.4 Extranet : Extranet vs. Intranet 33 Extranet Intranet Internal network that can be accessed externally. Internal network that can not be accessed externally. Extranet is extension of company's Intranet. Only limited users of a company. For limited external communication between customers, suppliers and business partners. Only for communication within a company

34. 4 .0 Internet Domain Name System (DNS) When DNS was not into existence, one had to download a Host file containing host names and their corresponding IP address . But with increase in number of hosts of internet, the size of host file also increased. This resulted in increased traffic on downloading this file. To solve this problem the DNS system was introduced . Domain Name System helps to resolve the host name to an address. It uses a hierarchical naming scheme and distributed database of IP addresses and associated names. 34

35. 4.1 Internet Domain Name System ( DNS): IP Address IP address is a unique logical address assigned to a machine over the network. An IP address exhibits the following properties: IP address is the unique address assigned to each host present on Internet. IP address is 32 bits (4 bytes) long. IP address consists of two components: network component and host component. Each of the 4 bytes is represented by a number from 0 to 255, separated with dots. For example 137.170.4.124 IP address is 32-bit number while on the other hand domain names are easy to remember names. For example, when we enter an email address we always enter a symbolic string such as [email protected] 35

36. 4.1 Internet Domain Name System ( DNS): Uniform Resource Locator (URL) Uniform Resource Locator (URL) refers to a web address which uniquely identifies a document over the internet . This document can be a web page, image, audio, video or anything else present on the web. For example, www.google.com/internet_technology/index.html is an URL to the index.html which is stored on Google web server under internet_technology directory . URL Types: There are two forms of URL as listed below : Absolute URL Relative URL 36

37. 4.1 Internet Domain Name System ( DNS): Uniform Resource Locator (URL ) … 1) Absolute URL Absolute URL is a complete address of a resource on the web. This completed address comprises of protocol used, server name, path name and file name . For example http:// www.google.com / internet_technology /index.htm . where : http is the protocol . google.com is the server name . index.htm is the file name. The protocol part tells the web browser how to handle the file. Similarly we have some other protocols also that can be used to create URL are : FTP https Gopher mailto news 37

38. 4.1 Internet Domain Name System ( DNS): Uniform Resource Locator (URL ) … 2) Relative URL Relative URL is a partial address of a webpage. Unlike absolute URL , the protocol and server part are omitted from relative URL . Relative URLs are used for internal links i.e. to create links to file that are part of same website as the WebPages on which you are placing the link. For example, to link an image on google.com / internet_technology / internet_referemce_models , we can use the relative URL which can take the form like / internet_technologies /internet-osi_model.jpg. 38

39. 4.1 Internet Domain Name System ( DNS): Uniform Resource Locator (URL ) … Difference between Absolute and Relative URL 39 Absolute URL Relative URL Used to link web pages on different websites Used to link web pages within the same website. Difficult to manage. Easy to Manage Changes when the server name or directory name changes Remains same even of we change the server name or directory name. Take time to access Comparatively faster to access.

40. 4.2 Internet Domain Name System ( DNS): Domain Name System Architecture The Domain name system comprises of Domain Names, Domain Name Space, Name Server that have been described below: Domain Names Domain Name is a symbolic string associated with an IP address . There are several domain names available; some of them are generic such as com, edu , gov , net etc , while some country level domain names such as au, in, za , us etc. 40

41. 4.2 Internet Domain Name System ( DNS): Domain Name System Architecture … The following table shows the Generic Top-Level Domain names: 41 Domain Name Meaning Com Commercial business Edu Education Gov U.S. government agency Int International entity Mil U.S. military Net Networking organization Org Non profit organization

42. 4.2 Internet Domain Name System ( DNS): Domain Name System Architecture … The following table shows the Country top-level domain names: 42 Domain Name Meaning au Australia in India cl Chile fr France us United States za South Africa uk United Kingdom jp Japan es Spain de Germany ca Canada ee Estonia hk Hong Kong

43. 4.3 Internet Domain Name System ( DNS): Domain Name Space The domain name space refers a hierarchy in the internet naming structure. This hierarchy has multiple levels (from 0 to 127), with a root at the top. The following diagram shows the domain name space hierarchy : In the above diagram each sub tree represents a domain. Each domain can be partitioned into sub domains and these can be further partitioned and so on. 43

44. 4.4 Internet Domain Name System ( DNS): Name Server Name server contains the DNS database . This database comprises of various names and their corresponding IP addresses. Since it is not possible for a single server to maintain entire DNS database , therefore, the information is distributed among many DNS servers . Hierarchy of server is same as hierarchy of names . The entire name space is divided into the zones 44

45. 4.5 Internet Domain Name System ( DNS): Zones Zone is collection of nodes (sub domains) under the main domain. The server maintains a database called zone file for every zone . If the domain is not further divided into sub domains then domain and zone refers to the same thing. The information about the nodes in the sub domain is stored in the servers at the lower levels however; the original server keeps reference to these lower levels of servers. 45

46. 4.6 Internet Domain Name System ( DNS): Types of Name Servers Following are the three categories of Name Servers that manages the entire Domain Name System : Root Server Primary Server Secondary Server Root Server Root Server is the top level server which consists of the entire DNS tree . It does not contain the information about domains but delegates the authority to the other server. Primary Servers Primary Server stores a file about its zone. It has authority to create, maintain, and update the zone file . Secondary Server Secondary Server transfers complete information about a zone from another server which may be primary or secondary server. The secondary server does not have authority to create or update a zone file. 46

47. 4.7 Internet Domain Name System ( DNS): DNS Working DNS translates the domain name into IP address automatically. Following steps will take you through the steps included in domain resolution process: When we type www.google.com into the browser, it asks the local DNS Server for its IP address. Here the local DNS is at ISP end. When the local DNS does not find the IP address of requested domain name, it forwards the request to the root DNS server and again enquires about IP address of it . The root DNS server replies with delegation that I do not know the IP address of www.google.com but know the IP address of DNS Server . The local DNS server then asks the com DNS Server the same question . The com DNS Server replies the same that it does not know the IP address of www.google.com but knows the address of google.com. Then the local DNS asks the google.com DNS server the same question . Then google.com DNS server replies with IP address of www.google.com . Now, the local DNS sends the IP address of www.google.com to the computer that sends the request. 47

48. 48 5.0 What Is The Internet ? Worldwide network of computer networks No central authority Quick communication & data transfer Size more than doubles annually Traffic increases more than 15%/ month Offers an enormous array of information

49. 49 Network of computer networks with TCP/IP as the common language 5.0 What Is The Internet ? …

50. 50 No one owns or runs the Internet . Every computer connected to the Internet is responsible for its own part. The webserver is responsible for maintaining only the backbone. https://www.marmathacollege.ac.in If something doesn’t work, you do not complain to the ‘management’ of the Internet. Instead you talk to the system administrators of the computer you are connected to. 5.1 Who Runs The Internet ? …

51. 51 Internet is network of networks. Users on one computer can access services from other computers. You can access a wide variety of these services. Each service can give you many kinds of information. In summary, The Internet is provides a way to move data from one computer to another. 5.1 The Internet Then …

52. 52 Search and Retrieve Documents Exchange e-mail (100 M email addresses) Download programs, demos and graphics Search databases of Companies and Government Read and Response to USENET groups (30,000 different topics) Real-time chat, web-phone and video conference 5.2 What Do You Do On The Internet ?

53. 53 Book an air ticket (best itinerary) Choose and order a book from a bookstore Order Food items. Buy Stocks (invest in companies) Watch a movie Make friends Visit e-malls, do e-shopping Watch what others are doing Display info about yourself Gossip Etc. 5.2 What Do You Do On The Internet ? ( Examples )

54. 54 On internet (network of networks), computers communicate with one another. Users of one computer can access services from another. You can use many methods to communicate with a computer somewhere else on the Internet . These methods used to communicate are called services because they service your requests . There are a wide variety of services, and each can give you many kinds of information. In summary the internet is a: way to move data (audio, video, etc ) a bunch of protocols (or rules for machines to communicate with each other) 5.3 What really is a Service ?

55. 55 All that we speak of internet fall into three categories: Clients Servers Content Software/Hardware that we use to browse the web, send mail, download files, etc. are called clients . Servers respond to clients requests. 5.4 Clients and Servers

56. 56 Internet Services allows us to access huge amount of information such as text, graphics, sound and software over the internet. Following diagram shows the four different categories of Internet Services . 6.0 Internet Services

57. 57 There are various Communication Services available that offer exchange of information with individuals or groups. The following table gives a brief introduction to these services: 6.1 Internet Services : Communication Services S.N. Service Description 1 Electronic Mail Used to send electronic message over the internet. 2 Telnet Used to log on to a remote computer that is attached to internet. 3 Newsgroup Offers a forum for people to discuss topics of common interests. 4 Internet Relay Chat (IRC) Allows the people from all over the world to communicate in real time. 5 Mailing Lists Used to organize group of internet users to share common information through e-mail. 6 Internet Telephony (VoIP) Allows the internet users to talk across internet to any PC equipped to receive the call. 7 Instant Messaging Offers real time chat between individuals and group of people. Eg . Yahoo messenger, MSN messenger.

58. 58 There exist several Information retrieval services offering easy access to information present on the internet. The following table gives a brief introduction to these services : 6.2 Internet Services : Information Retrieval Services S.N. Service Description 1 File Transfer Protocol (FTP) Enable the users to transfer files. 2 Archie It’s updated database of public FTP sites and their content. It helps to search a file by its name. 3 Gopher Used to search, retrieve, and display documents on remote sites. 4 Very Easy Rodent Oriented Netwide Index to Computer Achieved (VERONICA) VERONICA is gopher based resource. It allows access to the information resource stored on gopher’s servers.

59. 59 Web services allow exchange of information between applications on the web. Using web services , applications can easily interact with each other. The web services are offered using concept of Utility Computing. 6.3 Internet Services : Web Services

60. 60 WWW is also known as W3 . It offers a way to access documents spread over the several servers over the internet. These documents may contain texts, graphics, audio, video, hyperlinks. The hyperlinks allow the users to navigate between the documents. Video Conferencing Video conferencing or Video teleconferencing is a method of communicating by two-way video and audio transmission with help of telecommunication technologies . 6.4 Internet Services : World Wide Web (WWW )

61. 61 Modes of Video Conferencing 1) Point-to-Point This mode of conferencing connects two locations only. 6.4 Internet Services : World Wide Web (WWW ) …

62. 62 Modes of Video Conferencing … 1 ) Multi-point This mode of conferencing connects more than two locations through Multi-point Control Unit (MCU). 6.4 Internet Services : World Wide Web (WWW ) …

63. 63 User Browser Client Internet FTP server files Helper Applications Binary Graphics Audio Video Web Server 7 .0 Internet Applications: FTP and WWW

64. 64 Some most popular services on the Internet are: E-mail Telnet FTP WWW Others (Archie, Wais , Gopher, News and News Groups, Internet Relay Chat, Internet Phone, Net2phone, Video Conferencing, & Internet Collaborative Tools ) 7 .0.1 Available Services

65. 65 Email : Electronic mail Telnet: Remote login into computer networks FTP: File Transfer Protocol for transferring computer files WWW: World Wide Web Gopher: Searchable index, selectable index of documents USENET: Newsgroups with different subjects enable people with common interest to share information Chat: Real-time communications between people on the Internet 7 .0.1 Available Services …

66. 66 Most popular and widely used internet service. Has become a de-facto standard of communication within the corporate and beyond. Works between disparate systems like PC, Unix, Mac, etc. Latest e-mail standards let users attach files (audio, video, animation, etc ). Volume of data transferred is billions of bytes/day. 7.1 E-mail

67. 67 It is easy to send, read, reply to, and manage. It is convenient, global, economical and very fast. Studies have shown that recipients are more likely to reply to an e-mail message than a written request. E-mail can be read or written at any time, independent of time zones and business hours. 7.1 E-mail …

68. 68 Sender’s Mail Client Post Office Server (SMTP) Mail Server (POP3) Recipient’s Mail Server 7 .1.1 How e-mail works?

69. 69 Finding an e-mail Address Finger Whois Mailing list/Groups of e-mail addresses 7 .1.2 E-mail addresses / Mailing lists

70. 70 File Transfer Protocol Allows transfer of any type of file from the remote server to a local computer and vice versa File types could be ASCII or Binary All types of files from text to multimedia can be transferred. Two types of FTP : Secure and Anonymous can download or upload files without having an account on the machine. 7.2 FTP

71. 71 The Archie service is a collection of resource discovery tools that together provide an electronic directory service for locating information in an Internet environment. Archie creates a central index of files available on anonymous FTP sites around the Internet. The Archie servers connect to anonymous FTP sites that agree to participate and download lists of all the files on these sites. These lists of files are merged into a database, which users can then search. 7 .3 Archie

72. 72 WAIS stands for Wide Area Information Server and is pronounced “ways”. WAIS searches for words in documents. The core of the software is an indexer, used to create full-text indexes of files fed to it, and a server that can use those indexes to search for keywords or whole English expressions among the files indexed. 7 .4 WAIS

73. 73 The term Gopher refers to: - A network protocol - A server type - One of the many Gopher client applications . Gopher protocol and software allow for browsing information systems so that one doesn’t need to know exactly where the needed information is before looking for it. You do need to know the address of a Gopher server to get started. Very Easy Rodent Oriented Netwide Index to Computer Achieved (VERONICA) is a service that provides a (very large) index of titles of Gopher items from most servers throughout the Internet. 7 .5 Gopher

74. 74 Internet Service Provider (ISP) is a company offering access to internet. They offer various services: Internet Access Domain name registration Dial-up access Leased line access 8.0 I nternet Connectivity : Internet Service Providers (ISP)

75. 75 ISPs can broadly be classified into six categories as shown in the following diagram: 8.1 I nternet Connectivity : ISP Types

76. 76 Access providers They provide access to internet through telephone lines, cable Wi-Fi or fiber optics. Mailbox Provider Such providers offer mailbox hosting services. Hosting ISPs Hosting ISPs offers e-mail, and other web hosting services such as virtual machines, clouds etc. Virtual ISPs Such ISPs offer internet access via other ISP services. Free ISPs Free ISPs do not charge for internet services. 8.1 I nternet Connectivity : ISP Types …

77. 77 There exist several ways to connect to the internet. Following are these connection types available : Dial-up Connection ISDN DSL Cable TV Internet connections Satellite Internet connections Wireless Internet Connections 8.2 I nternet Connectivity : Connection Types

78. 78 Dial-up connection uses telephone line to connect PC to the internet. It requires a modem to setup dial-up connection . This modem works as an interface between PC and the telephone line. There is also a communication program that instructs the modem to make a call to specific number provided by an ISP . Dial-up connection uses either of the following protocols : Serial Line Internet Protocol (SLIP ) Point to Point Protocol (PPP) 8.2.1 I nternet Connectivity : 1 ) Dial-up Connection

79. 79 The following diagram shows the accessing internet using modem: 8.2.1 Internet Connectivity : 1) Dial-up Connection …

80. 80 ISDN is acronym of Integrated Services Digital Network . It establishes the connection using the phone lines which carry digital signals instead of analog signals. There are two techniques to deliver ISDN services : Basic Rate Interface (BRI ) Primary Rate Interface (PRI ) Key points : The BRI ISDN consists of three distinct channels on a single ISDN line: 1 to 64kbps B (Bearer) channel and one 16kbps D (Delta or Data) channels . The PRI ISDN consists of 23 B channels and one D channels with both have operating capacity of 64kbps individually making a total transmission rate of 1.54Mbps . 8.2.2 I nternet Connectivity : 2 ) ISDN

81. 81 The following diagram shows the accessing internet using ISDN connection: 8.2.2 I nternet Connectivity : 2) ISDN …

82. 82 DSL is acronym of Digital Subscriber Line . It is a form of broadband connection as it provides connection over ordinary telephone lines . Following are the several versions of DSL technique available today: Asymmetric DSL (ADSL ) Symmetric DSL (SDSL ) High bit-rate DSL (HDSL ) Rate adaptive DSL (RDSL ) Very high bit-rate DSL (VDSL ) ISDN DSL (IDSL) All of the above mentioned technologies differ in their upload and download speed, bit transfer rate and level of service. 8.2.3 I nternet Connectivity : 3) DSL

83. 83 The following diagram shows that how we can connect to internet using DSL technology: 8.2.3 Internet Connectivity : 3) DSL …

84. 84 Cable TV Internet connection is provided through Cable TV lines. It uses coaxial cable which is capable of transferring data at much higher speed than common telephone line. Key Points : A cable modem is used to access this service, provided by the cable operator . The Cable modem comprises of two connections: one for internet service and other for Cable TV signals . Since Cable TV internet connections share a set amount of bandwidth with a group of customers, therefore, data transfer rate also depends on number of customers using the internet at the same time. 8.2.4 I nternet Connectivity : 4 ) Cable TV Internet Connection

85. 85 The following diagram shows that how internet is accessed using Cable TV connection: 8.2.4 I nternet Connectivity : 4 ) Cable TV Internet Connection …

86. 86 Satellite Internet connection offers high speed connection to the internet. There are two types of satellite internet connection : one way connection or two way connection . In one way connection , we can only download data but if we want to upload, we need a dialup access through ISP over telephone line. In two way connection , we can download and upload the data by the satellite. It does not require any dialup connection. 8.2.5 I nternet Connectivity : 5 ) Satellite Internet Connection

87. 87 The following diagram shows how internet is accessed using satellite internet connection: 8.2.5 I nternet Connectivity : 5 ) Satellite Internet Connection …

88. 88 Wireless Internet Connection makes use of radio frequency bands to connect to the internet and offers a very high speed. The wireless internet connection can be obtained by either WiFi or Bluetooth. Key Points: Wi Fi wireless technology is based on IEEE 802.11 standards which allow the electronic device to connect to the internet. Bluetooth wireless technology makes use of short-wavelength radio waves and helps to create personal area network (PAN). 8.2.6 Internet Connectivity : 6 ) Wireless Internet Connection